Electrode assembly and preparation method thereof, alkali metal battery, electric device and energy storage device

Abstract

The invention relates to the technical field of batteries, and discloses an electrode assembly and a preparation method thereof, an alkali metal battery, a power utilization device and an energy storage device. The electrode assembly comprises a positive pole piece, a negative pole piece, an isolating membrane and a supporting layer, the supporting layer is arranged on the surface of a base body, and the surface of the base body comprises any one of the two opposite surfaces of the negative pole piece and the isolating membrane; the supporting layer is provided with a plurality of through holes, and the through holes are formed in the thickness direction of the supporting layer in a penetrating mode. And / or the supporting layer comprises a plurality of supporting units, and a gap is formed between every two adjacent supporting units. The through holes in the supporting layer or gaps between the supporting units are used for containing deposited alkali metal, and space is reserved for volume change of the alkali metal. In addition, the gaps between the through hole structures or the supporting units can provide more active sites for nucleation of the alkali metal, and formation of more uniform and compact deposition of the alkali metal is facilitated, so that the cycle performance of the battery can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to an electrode assembly and its preparation method, an alkali metal battery, an electrical device, and an energy storage device. Background Technology

[0002] During the charging and discharging process of a battery, the negative electrode material undergoes the insertion and extraction of alkali metal ions, resulting in a significant change in the volume of the negative electrode material. This phenomenon is called deposition expansion.

[0003] During deposition, the negative electrode material in a battery expands and becomes prone to yielding under stress. If this volume change is not effectively mitigated, it can cause cell distortion, leading to increased internal resistance and even puncturing the separator, causing an internal short circuit. Therefore, battery design requires not only high interface adhesion between the cathode, separator, and anode, but also a buffer space to accommodate the volume changes of the alkali metal negative electrode during charging and discharging. High interface adhesion means that the contact interfaces between components are tight and consistent, which facilitates rapid ion transport and helps maintain the stability of the battery's internal structure.

[0004] Therefore, it is necessary to design an internal device with controllable thickness inside the cell that can provide a buffer space for the deposition and expansion of alkali metals, so as to prevent the internal structure of the battery from being damaged due to the expansion of the negative electrode, thereby affecting the cycle performance of the battery. Summary of the Invention

[0005] In view of the above problems, this application provides an electrode assembly and its preparation method, an alkali metal battery, and an electrical device, aiming to solve the problem of poor cycle performance caused by the volume expansion of the negative electrode.

[0006] In a first aspect, embodiments of this application provide an electrode assembly, including a positive electrode sheet, a negative electrode sheet, a separator, and a support layer. The support layer is disposed on a substrate surface, and the substrate surface includes either the negative electrode sheet or the separator surface that are opposite to each other. The support layer has a plurality of through holes, which are disposed through the thickness direction of the support layer. And / or, the support layer includes a plurality of support units, with a gap between two adjacent support units.

[0007] In the technical solution of this application embodiment, the support layer is located between the negative electrode sheet and the separator, and can be disposed on the negative electrode sheet or on the separator. The provision of the support layer can improve the controllability of the distance between the negative electrode sheet and the separator. The through holes in the support layer are used to accommodate the deposited alkali metal and reserve space for the volume change of the alkali metal. Alternatively, the gap between every two adjacent support units can also provide buffer space for the deposition expansion of the alkali metal. The support unit refers to the basic component of the support layer, and the gap between the support units is equivalent to opening open channels in the support layer to divide the support layer into several support units. The through hole structure or the gap between the support units provides a smooth transport channel for alkali metal ions in the electrolyte, which helps to reduce the resistance of ion transport, enabling alkali metal ions to reach and deposit on the surface of the negative electrode sheet more quickly. The through hole structure or the gap between the support units can also provide more active sites for the nucleation of alkali metal, which helps to form a more uniform and dense deposition of alkali metal. Therefore, the support layer in this embodiment can provide space and channels for the deposition of alkali metals, and is conducive to the dense deposition of alkali metals, thereby effectively improving the cycle performance of the battery.

[0008] In some embodiments, the support layer is a 3D-printed structure. A 3D-printed structure is a highly precise and stable integrated structure with dimensions reaching the micrometer or even nanometer level, making it suitable for applications in the battery field.

[0009] In some embodiments, the pore size of the through-hole is 2 μm to 1500 μm; and / or, the width of the gap between two adjacent support units is 2 μm to 1500 μm. Thus, the porosity of the support layer provides a suitable buffer space for the volume expansion of the negative electrode material, while also enabling the support layer structure to have good stability. Furthermore, controlling the pore size or the gap between support units within the above range helps to form a denser and more uniform deposition layer.

[0010] In some embodiments, the aperture of the through-hole is 2 μm to 300 μm; and / or, the width of the gap between two adjacent support units is 2 μm to 300 μm. This further facilitates the formation of a dense and uniform deposition layer.

[0011] In some embodiments, the area of ​​the support layer covering the surface of the substrate accounts for 5% to 50% of the surface area of ​​the substrate. Thus, the gaps between the through-holes or support units can provide more space to accommodate volume changes in the electrode material, thereby better mitigating the stress caused by these volume changes, improving the structural stability of the electrode assembly, and further alleviating the problem of poor battery cycle performance caused by volume expansion.

[0012] In some embodiments, the thickness of the support layer is 5 μm to 300 μm. Thus, the support layer provides a suitable spacing between the negative electrode and the separator, accommodating the expansion and deformation of the alkali metal, while also maintaining the structural stability of the electrode assembly.

[0013] In some embodiments, the material of the support layer includes a polymer and a conductive agent; wherein the polymer includes at least one selected from polyacrylate, polypropylene, and polyethylene; and / or the conductive agent includes at least one selected from conductive carbon black, carbon fiber, carbon nanotubes, and graphene. Polyacrylate, polypropylene, and polyethylene are all polymer materials with good chemical stability, high mechanical strength, and corrosion resistance, suitable for use in batteries, and can help the support layer maintain shape stability in the battery assembly. The addition of a conductive agent can provide conductivity to the support layer, enabling more efficient transport of alkali metal ions and charges by providing good conductive channels.

[0014] In some embodiments, the support layer has an affinity layer located in the thickness direction, the affinity layer comprising a metal element with an affinity for alkali metals; the affinity layer is located at the end of the support layer closer to the negative electrode. This allows the affinity of the support layer for alkali metals to exhibit a gradient change in the thickness direction, i.e., in the support layer structure, the affinity for alkali metals increases stepwise from the distance from the negative electrode. This affinity gradient distribution can guide alkali metal ions to preferentially deposit in the region closer to the negative electrode during the deposition process, thereby avoiding excessively high local concentrations that could lead to dendrite growth, achieving dense and smooth deposition of alkali metals, and further improving the cycle performance of the battery.

[0015] In some embodiments, the metal element includes at least one selected from Au, Ag, Mg, Zn, Sn, Sb, In, and Ti; and / or, based on 100% of the total mass of the support layer, the mass percentage of the metal element is 0.05% to 5%. Thus, the design of the affinity layer allows the support layer to exhibit an affinity gradient distribution, thereby helping to induce alkali metal ions to preferentially deposit on the affinity layer side during charge and discharge, thereby suppressing dendrite growth and improving the cycle performance of the battery.

[0016] In some embodiments, the thickness of the affinity layer is 0.1 μm to 10 μm. This facilitates the preferential and uniform deposition of alkali metals on one side of the affinity layer, suppressing dendrite formation.

[0017] In some embodiments, the support layer has a polymer layer located in the thickness direction; the polymer layer is located at the end of the support layer opposite to the negative electrode sheet. This allows the support layer to be insulated at its end in contact with or near the separator, preventing direct contact between the negative electrode sheet and the separator, thus preventing short circuits. It also prevents alkali metals from growing and depositing near the separator, reducing the risk of puncturing the separator.

[0018] In some embodiments, the thickness of the polymer layer accounts for 1% to 50% of the thickness of the support layer; and / or, the material of the polymer layer includes at least one of polyacrylate, polypropylene, and polyethylene. Thus, the polymer layer can both prevent short circuits and avoid increasing the internal resistance of the battery, without affecting its electrochemical performance.

[0019] In some embodiments, the support layer has a plurality of uniformly distributed, identically structured through-holes; and / or, the support layer comprises a plurality of identical support units arranged in an array. This means that the support layer has uniformly distributed pores, which allows for more uniform distribution of the electrolyte, facilitates uniform deposition of alkali metals, helps suppress dendrite growth, and, simultaneously, the uniformly distributed pores help alleviate internal stress caused by volume expansion, further promoting improved cycle stability of the battery.

[0020] Secondly, embodiments of this application provide a method for preparing an electrode assembly, comprising the following steps:

[0021] Based on the preset three-dimensional model of the support layer, the support layer is obtained by 3D printing on either of the two opposing surfaces of the negative electrode sheet and the separator, using polymer and conductive agent as raw materials.

[0022] The support layer has a plurality of through holes, which are disposed through the thickness of the support layer; and / or, the support layer includes a plurality of support units, with a gap between two adjacent support units;

[0023] The positive electrode, separator, and negative electrode are assembled in sequence to form the electrode assembly.

[0024] This application embodiment uses 3D printing technology to manufacture the support layer, which can precisely control the structure and size. At the same time, it can also select appropriate materials to manufacture the support layer according to the specific needs of the battery. Compared with traditional manufacturing methods, 3D printing technology can more accurately manufacture the required shape and structure, and has high production efficiency. The support layer manufactured between the negative electrode sheet and the separator can improve the cycle performance of the battery.

[0025] In some embodiments, the 3D printing process parameters are as follows: nozzle size is 5μm to 100μm; printing speed is 1m / min to 10m / min. This method allows for the printing of finer structures and smaller gaps, improving print detail and quality. The printed support layer guides the uniform and dense deposition of alkali metals and reduces the volume expansion of the negative electrode, thereby improving the battery's cycle performance.

[0026] Thirdly, embodiments of this application provide an alkali metal battery, including the electrode assembly described above. Due to the use of the electrode assembly, the battery's cycle expansion force is significantly improved, and its cycle performance is enhanced.

[0027] Fourthly, embodiments of this application provide an electrical device including the aforementioned alkali metal battery. By employing the alkali metal battery of this application, the operational stability of the electrical device is improved.

[0028] Fifthly, embodiments of this application provide an energy storage device including the aforementioned alkali metal battery. By employing the alkali metal battery of this application, the overall performance of the energy storage device is improved.

[0029] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0030] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0031] Figure 1 This is a cross-sectional view of the electrode assembly in some embodiments of this application;

[0032] Figure 2 This is a cross-sectional view of the electrode assembly in some embodiments of this application;

[0033] Figure 3 This is a cross-sectional view of the electrode assembly in some embodiments of this application;

[0034] Figure 4 This is a cross-sectional view of the electrode assembly in some embodiments of this application;

[0035] Figure 5 This is a cross-sectional view of the electrode assembly in some embodiments of this application;

[0036] Figure 6 This is a top view of the support layer structure of some embodiments of this application;

[0037] Figure 7 This is a top view of the support layer structure of some embodiments of this application;

[0038] Figure 8 This is a top view of the support layer structure of some embodiments of this application;

[0039] Figure 9 This is a top view of the support layer structure of some embodiments of this application;

[0040] Figure 10 This is a schematic diagram of the structure of the electrode sheet in some embodiments of this application;

[0041] Figure 11 This is a schematic diagram of the structure of the electrode assembly in some embodiments of this application;

[0042] Figure 12 This is a schematic diagram of the vehicle structure according to some embodiments of this application;

[0043] The reference numerals in the detailed embodiments are as follows:

[0044] 10-Electrode; 1-Current collector; 2-Active material layer;

[0045] 20 - Electrode assembly; 101 - Negative electrode; 102 - Positive electrode; 103 - Separator; 104 - Negative electrode tab; 105 - Positive electrode tab;

[0046] 40 - Battery; 50 - Electrical device; 501 - Controller; 502 - Motor;

[0047] 100 - Substrate surface; 200 - Support layer; 201 - Support unit; 210 - Through hole; 220 - Gap between two adjacent support units; 230 - Affinity layer; 240 - Polymer layer. Detailed Implementation

[0048] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0050] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0051] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0053] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0054] In the description of the embodiments of this application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0055] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0056] The deposition of alkali metals on the negative electrode of a battery is often accompanied by significant volume changes. If these volume changes are not effectively mitigated, they can easily lead to the destruction of the negative electrode structure, thereby reducing the cycle performance of the battery. Therefore, it is necessary to provide a device for the negative electrode to accommodate volume expansion, so that the negative electrode material has a certain buffer space when undergoing volume changes.

[0057] Based on this, this application provides an electrode assembly comprising a positive electrode, a negative electrode, a separator, and a support layer. Please refer to... Figures 1-4 , Figures 1-4 This is a partial structural schematic diagram of an electrode assembly according to some embodiments of this application. A support layer 200 is disposed on a substrate surface 100, which includes either the negative electrode sheet 101 or the separator 103, which are opposite to each other; as shown... Figure 1 and Figure 2 As shown, the support layer 200 has a plurality of through holes 210, which are disposed through the support layer 200 in the thickness direction X; and / or, as Figure 3 and Figure 4 As shown, the support layer 200 includes a plurality of support units 201, and there is a gap 220 between two adjacent support units 201.

[0058] The support layer in this embodiment is disposed on the surface of a substrate, which can be a negative electrode sheet or a separator. Since the negative electrode sheet and the separator have two opposing surfaces, the support layer in this embodiment can be disposed on the surface of the negative electrode sheet facing the separator, or on the surface of the separator facing the negative electrode sheet.

[0059] Figure 6 This is a top view of the support layer in one embodiment of this application. The support layer 200 is a mesh structure with multiple through holes 210, and the cross-sectional shape of the through holes is square. In other embodiments, the cross-sectional shape of the through holes can also be any regular shape such as circular, rectangular, or triangular.

[0060] Figures 7-9This is a top view of the support layer in some other embodiments of this application. The support layer 200 is composed of a plurality of support units 201. The cross-section of the support unit 201 can be any shape such as rectangular, circular, polygonal, or cross-shaped. The gap 220 between each two adjacent support units 201 means that the two adjacent support units are not connected, but have a spacer channel between them. The existence of the spacer channel provides a buffer space for the deposition and expansion of alkali metals.

[0061] In other embodiments, the support layer may be a combination of the above-described mesh structure and support units, and the combination method is not limited.

[0062] As an example, such as Figure 1 An electrode assembly is shown, including a positive electrode (not shown), a negative electrode 101, a separator 103, and a support layer 200. The support layer 200 is disposed on the surface of the negative electrode 101 facing the separator 103. The support layer 200 has a plurality of through holes 210, which are disposed through the thickness direction X of the support layer 200.

[0063] As an example, such as Figure 2 An electrode assembly is shown, including a positive electrode (not shown), a negative electrode 101, a separator 103, and a support layer 200. The support layer 200 is disposed on the surface of the separator 103 facing the negative electrode 101. The support layer 200 has a plurality of through holes 210, which are disposed through the thickness direction X of the support layer 200.

[0064] As an example, such as Figure 3 An electrode assembly is shown, including a positive electrode (not shown), a negative electrode 101, a separator 103, and a support layer 200. The support layer 200 is disposed on the surface of the negative electrode 101 facing the separator 103. The support layer 200 includes a plurality of support units 201, and there is a gap 220 between two adjacent support units 201.

[0065] As an example, such as Figure 4 An electrode assembly is shown, including a positive electrode (not shown), a negative electrode 101, a separator 103, and a support layer 200. The support layer 200 is disposed on the surface of the separator 103 facing the negative electrode 101. The support layer 200 includes a plurality of support units 201, and there is a gap 220 between two adjacent support units 201.

[0066] As an example, such as Figure 5An electrode assembly is shown, including a positive electrode (not shown), a negative electrode 101, a separator 103, and a support layer 200. The support layer 200 is disposed on the surface of the negative electrode 101 facing the separator 103. The support layer 200 may also be in contact with the separator 103. The support layer 200 has a plurality of through holes 210, which are disposed through the thickness direction X of the support layer 200.

[0067] In the electrode assembly of this application embodiment, a support layer is disposed between the negative electrode sheet and the separator. The support layer has a through-hole structure or gaps between the support units. The through-hole structure of the support layer is a hole that penetrates the entire support layer in the thickness direction. This through-hole structure is relatively simple and orderly, helping to provide more transport channels for alkali metal ions. These through-holes facilitate rapid and uniform ion transport between the negative electrode and the electrolyte, reducing the generation of local concentration gradients. The through-hole structure can also guide the deposition behavior of alkali metal ions on the negative electrode, making the deposition process more uniform and orderly. This deposition helps reduce stress concentration and volume changes caused by uneven deposition, alleviating the volume expansion of the negative electrode material. Furthermore, the support layer can also be composed of several support units, with gaps between adjacent support units forming channels. These channels provide space for the deposition of the negative electrode material, absorbing and mitigating the stress caused by volume expansion. Moreover, these gaps facilitate the uniform deposition of alkali metals on the negative electrode sheet. When alkali metal ions are transported to the negative electrode surface through the gap channels, they tend to form a uniform deposition layer around the channels rather than excessively depositing dendrites in certain local areas, thus helping to achieve dense deposition of alkali metals and further mitigating the volume expansion of the negative electrode. Therefore, by setting the above-mentioned support layer structure between the negative electrode sheet and the separator, the embodiments of this application can alleviate the volume change of the alkali metal negative electrode material, significantly improve the cycle expansion force of the battery, and enhance the cycle performance.

[0068] In some embodiments, the support layer 200 is a 3D printed structure. A 3D printed structure is a highly precise and stable integrated structure with dimensions that can reach the micrometer or even nanometer level. This enables high-precision manufacturing of the support layer structure, including its thickness, shape, and pore structure, thereby optimizing battery performance.

[0069] In some embodiments, the aperture of the through-hole 210 is 2 μm to 1500 μm. The aperture of a through-hole refers to the size of the hole. For example, when the through-hole is circular, the aperture refers to the diameter of the circle; when the through-hole is square, the aperture refers to the side length of the square; when the through-hole is rectangular, the aperture can refer to the length of either the longer or shorter side of the rectangle; when the through-hole is triangular, the aperture refers to the height of the triangle. As examples, the aperture of the through-hole can be typical but not limiting values ​​such as 2 μm, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 500 μm, 750 μm, 1000 μm, and 1500 μm. If the pore size is too small, it will not provide sufficient space for the deposition of metallic sodium; if the pore size is too large, it may reduce the reversibility of the alkali metal dissolution process. The dissolution of alkali metals is the reverse process of deposition, which occurs during battery discharge. In this process, the alkali metal loses electrons at the negative electrode surface, is oxidized into alkali metal ions, and dissolves in the electrolyte solution. Therefore, the pore size within the aforementioned range is beneficial for improving the dense deposition behavior of metallic sodium and the reversibility of its dissolution, thereby improving cycle performance.

[0070] In some optional embodiments, the pore size of the through-hole 210 is 2 μm to 300 μm. This is more conducive to improving the dense deposition behavior of metallic sodium and the reversibility of its dissolution, thereby further improving cycle performance.

[0071] In some embodiments, the width of the gap between two adjacent support units 201 is 2 μm to 1500 μm. The width of the gap refers to the shortest distance between the edges of two adjacent support units. For example, when the support unit is a cylinder, the shortest distance between the edges of two circles can be equal to the distance between the centers of the two circles minus the sum of their radii. When the support unit is a cuboid, the relative positions of the two cuboids can be observed, and a point on the first cuboid that is closest to the second cuboid can be selected. The nearest point on the second cuboid corresponding to the selected point can then be found, and the distance between the two points can be determined. As an example, the width of the gap between two adjacent support units can be typical but not limiting values ​​such as 2 μm, 10 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 500 μm, 750 μm, 1000 μm, and 1500 μm. The width of the gap between two adjacent support units within the aforementioned range is also beneficial for the adhesion and deposition of alkali metals on the substrate surface, and can also provide a shorter ion diffusion path, improving the density and uniformity of the deposited layer. Therefore, the aforementioned gap size range is beneficial for improving the transport and storage efficiency of alkali metal ions.

[0072] In some embodiments, the width of the gap between two adjacent support units 201 is 2 μm to 300 μm. This is more conducive to improving the transport and storage efficiency of alkali metal ions.

[0073] In some embodiments, the area of ​​the support layer 200 covering the substrate surface 100 accounts for 5% to 50% of the area of ​​the substrate surface 100. This means that the uncovered area of ​​the substrate surface accounts for 50% to 95%, and the uncovered portion of the substrate surface is the area where the pores of the support layer are located. As an example, the ratio of the area of ​​the support layer covering the substrate surface to the total area of ​​the substrate surface can be typical but not limiting values ​​such as 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%. If the area of ​​the support layer covering the substrate surface is too large, in order to provide more buffer space for alkali metal deposition, the support layer may be designed to be too thick, resulting in additional volumetric energy density loss. Through the above technical solution, the pores of the support layer facilitate better electrolyte penetration and distribution, promote dense and uniform deposition of alkali metals, and help maintain the structural stability of the support layer, thereby improving the cycle stability of the battery.

[0074] In some embodiments, the thickness of the support layer 200 is 5 μm to 300 μm. As examples, the thickness of the support layer can be typical but not limiting values ​​such as 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, and 300 μm. The support layer serves to maintain a controllable distance between the negative electrode and the separator, while also supporting and accommodating the negative electrode active material. It also participates in the adsorption and desorption processes of alkali metal ions. When the thickness of the support layer is within the aforementioned range, it can better adsorb alkali metal ions, thereby improving the battery's capacity and energy density, and enhancing the structural stability of the electrode assembly.

[0075] In some embodiments, the support layer 200 is made of a polymer and a conductive agent. Polymer materials possess good mechanical properties, such as flexibility and impact resistance, enabling them to maintain the stability of the negative electrode during battery charging and discharging, preventing structural damage caused by volume changes in the negative electrode. Furthermore, polymer materials generally exhibit good stability in electrochemical environments, resisting corrosion and oxidation by the electrolyte. The addition of the conductive agent provides conductivity to the support layer. A support layer with good conductivity reduces the resistance during electron transport, allowing electrons to flow more smoothly within the negative electrode, thereby improving the overall conductivity of the battery. The combination of polymer and conductive agent gives the support layer suitable conductivity and mechanical properties for the battery. Moreover, polymer materials typically have a lower density than metal materials, reducing the overall weight of the battery and increasing energy density. Additionally, polymers have good processing properties, allowing the support layer to be formed into desired shapes through various methods.

[0076] Optionally, the polymer may be selected from at least one of polyacrylate, polypropylene, and polyethylene. The above polymer materials exhibit good stability in electrochemical environments and can resist corrosion and oxidation by the electrolyte, thereby protecting the negative electrode material and extending the battery's lifespan. The above materials also have good flexibility, can adapt to volume changes of the negative electrode material during charging and discharging, and can resist fracture or detachment caused by mechanical stress, which helps maintain the stability of the electrode assembly.

[0077] Optionally, the conductive agent includes at least one of conductive carbon black, carbon fiber, carbon nanotubes, and graphene. These conductive agents possess excellent conductivity, reducing the contact resistance of the support layer and accelerating electron movement, thereby improving the battery's charge / discharge efficiency and capacity. Simultaneously, these conductive agents also possess a certain degree of mechanical strength, enhancing the structural strength of the support layer and improving its overall stability. Furthermore, these conductive agents exhibit good flexibility and impact resistance, enabling them to adapt to volume changes in the negative electrode material during charge / discharge, thus improving the battery's charge / discharge efficiency and cycle stability.

[0078] In some embodiments, the mass ratio of polymer to conductive agent is 9:1 to 1:1. As examples, typical but not limiting values ​​for the mass ratio can be 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, etc. As the mass ratio of conductive agent in the support layer material increases, the conductivity of the support layer improves; however, excessive addition of conductive agent may lead to a decrease in mechanical properties. Therefore, by employing the above technical solution, the support layer can possess suitable conductivity and mechanical properties.

[0079] In some embodiments, such as Figure 5As shown, the support layer 200 has an affinity layer 230 located in the thickness direction. The affinity layer 230 contains a metal element with an affinity for alkali metals. The affinity layer 230 is located at one end of the support layer 200 near the negative electrode 101. The affinity layer 230 located in the thickness direction refers to a layer in the X direction of the support layer 200 structure. "Affinity" refers to an affinity for alkali metals. An affinity for alkali metals means that when an alkali metal is brought into contact with the affinity layer material, the nucleation barrier of alkali metal atoms on the surface of the affinity layer material is significantly reduced. This is because the affinity material can provide more energy-stable nucleation sites, making it easier for alkali metal atoms to deposit at these sites. Furthermore, the affinity material can induce uniform diffusion of alkali metal ions on the surface of the affinity layer material, thereby contributing to the formation of a uniform and dense deposition layer.

[0080] In this embodiment, the affinity layer 230 is disposed near the surface of the negative electrode 101. This structural design forms an affinity gradient distribution structure for alkali metals, which can induce alkali metals to preferentially adsorb and deposit in a section near the negative electrode 101, forming a gradient deposition behavior, thereby regulating the deposition morphology of alkali metals, guiding the uniform deposition of alkali metal ions, and improving the cycle performance of the battery.

[0081] In some embodiments, the metallic element includes at least one selected from Au, Ag, Mg, Zn, Sn, Sb, In, and Ti. Noble metals such as Au and Ag have an affinity for alkali metals due to their unique chemical properties. Elements such as Mg, Zn, Sn, Sb, In, and Ti, and their compounds, can chemically interact with alkali metals, thus exhibiting an affinity for them. The aforementioned metallic elements can be derived from corresponding elemental metals, alloys, metal oxides, etc. For example, an affinity layer containing Au can be achieved by adding elemental Au, an Au-containing alloy, or an Au-containing oxide to the affinity layer.

[0082] In some embodiments, the mass percentage of the metal element, based on 100% of the total mass of the support layer 200, is 0.05% to 5%. As examples, the mass percentage of the metal element can be typical but not limiting values ​​such as 0.05%, 0.10%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, and 5%. In affinity gradient design, if the amount of metal element added is too small, the affinity performance of the affinity layer for alkali metals cannot be effectively improved; however, excessive addition may lead to a decrease in the conductivity of the affinity layer. When the amount of metal element added is within the above range, the support layer 200 can exhibit an affinity gradient distribution, thereby helping to induce alkali metal ions to preferentially deposit on one side of the affinity layer 230 during charge and discharge, thereby suppressing dendrite growth and improving the cycle performance of the battery.

[0083] In some embodiments, the thickness of the affinity layer 230 is 0.1 μm to 10 μm. As examples, the thickness of the affinity layer 230 can be typical but not limiting values ​​such as 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm. A thickness of the affinity layer 230 within the above range is beneficial for inducing preferential and uniform deposition of alkali metals on one side of the affinity layer, thus suppressing dendrite formation.

[0084] In some optional embodiments, the thickness of the affinity layer 230 is 0.1 μm to 3 μm. When the thickness of the affinity layer is within the above range, it can further induce uniform deposition of alkali metals and suppress dendrite formation.

[0085] In some embodiments, such as Figure 5 As shown, the support layer 200 has a polymer layer 240 located in the thickness direction; the polymer layer 240 is located at the end of the support layer 200 opposite to the negative electrode 101. The polymer layer 240 located in the thickness direction refers to a layer in the X direction of the support layer 200 structure, and the polymer layer 240 is made of polymer material. Since polymers typically have a certain degree of insulation and relatively low ionic conductivity, this means that it will affect the deposition rate of alkali metals. The end opposite to the negative electrode 101 means that the polymer layer 240 is located at the end close to the separator 103. By providing the polymer layer 240 at the end close to the separator 103, the support layer 200 can be insulated at its contact or near the separator, preventing alkali metals from growing and depositing at the end close to the separator 103 first, thereby preventing the risk of internal short circuits in the battery due to dendrites piercing the separator.

[0086] In some embodiments, the thickness of the polymer layer 240 accounts for 1% to 50% of the thickness of the support layer 200. As examples, the thickness percentage of the polymer layer can be typical but not limiting values ​​such as 1%, 5%, 10%, 20%, 30%, 40%, and 50%. A thicker polymer layer can provide better electrical isolation and protection against the risk of short circuits, but it also increases the internal resistance and weight of the battery. By controlling the thickness percentage of the polymer layer within the aforementioned range, both short circuits can be prevented and the battery can have better electrochemical performance.

[0087] In some embodiments, the polymer layer 240 is made of at least one of polyacrylate, polypropylene, and polyethylene. These polymer materials possess good insulation properties and chemical stability, as well as good processability, making them suitable for use as insulating materials in batteries.

[0088] In some embodiments, such as Figure 6As shown, the support layer 200 has a number of uniformly distributed through holes 210 with identical structures. Uniform distribution means that the through holes 210 are evenly distributed on the support layer 200, arranged at equal intervals or following a certain regularity, presenting a neat and balanced form without obvious clustering or sparse areas. For example, in the length direction (Y direction) of the support layer 200, every two adjacent through holes 210 are arranged with a spacing of d1; in the width direction (Z direction) of the support layer 200, every two adjacent through holes 210 are arranged with a spacing of d2. d1 and d2 can be equal or unequal. A through hole 210 refers to a channel that penetrates from the top layer to the bottom layer of the support layer 200. Identical through holes 210 mean that the pore diameter structural parameters of the through holes 210 are consistent. This support layer 200 design ensures that ions in the electrolyte follow a consistent transport path, preventing excessively high or low ion concentrations in certain areas. It significantly reduces the uneven flux of alkali metals during deposition, resulting in uniform and dense deposition of alkali metals on the negative electrode surface. Simultaneously, the uniform pore structure helps reduce local current density and dendrite growth. Since dendrites are typically sharp deposits, they can easily pierce the separator, causing internal short circuits. Dense deposition inhibits dendrite growth, further reducing the risk of internal short circuits caused by dendrites piercing the separator. Therefore, uniformly distributed pores with the same pore size promote uniform deposition of alkali metals, thereby improving the battery's cycle performance.

[0089] In some embodiments, such as Figure 8 As shown, the support layer 200 includes several identical support units 201 arranged in an array. Identical support units 201 mean that the support units 201 maintain consistency in size, shape, and material selection. Arranging them in an array means that the support units 201 are arranged according to certain rules and spacing. For example, every two adjacent support units 201 in the length direction (Y direction) of the support layer 200 are arranged with a spacing of d3; every two adjacent support units 201 in the width direction (Z direction) of the support layer 200 are arranged with a spacing of d4. d3 and d4 can be equal or unequal. Simultaneously, because the support units 201 are arranged in a regular pattern, the gaps 220 between adjacent support units 201 are also uniformly distributed, thereby guiding the uniform and dense deposition of alkali metal, reducing the volume expansion of the negative electrode, and improving the cycle performance of the alkali metal battery.

[0090] Secondly, embodiments of this application provide a method for fabricating an electrode assembly, comprising the following steps: based on a preset three-dimensional model of a support layer; using polymer and conductive agent as raw materials, 3D printing is performed on either of the two opposing surfaces of the negative electrode sheet and the separator to obtain the support layer. The support layer has a plurality of through holes, which are disposed through the thickness direction of the support layer; and / or, the support layer includes a plurality of support units, with a gap between adjacent support units; and the positive electrode sheet, the separator, and the negative electrode sheet are assembled sequentially into an electrode assembly.

[0091] This application embodiment utilizes 3D printing technology to construct support layers of various shapes and structures. Furthermore, through a layer-by-layer construction method, 3D printing allows for highly precise dimensions and shapes of the support layers. 3D printing technology supports the printing of various materials, such as metals, ceramics, polymers, and composite materials, thus allowing the selection of the most suitable material to manufacture the support layer based on application requirements. Moreover, the formulation of the printing material and printing parameters can be adjusted according to the conductivity and mechanical strength of the support layer.

[0092] In this embodiment, a support layer with support and structural integrity is prepared on the negative electrode sheet or separator using 3D printing technology. The support layer has a regular or irregular through-hole structure or a regular or irregular support unit structure, which provides structural support for the negative electrode sheet to accommodate the expansion of alkali metal deposition. This can prevent the cell assembly from deforming during charging and discharging. By precisely controlling the shape and structure of the support layer, the current distribution inside the battery can be optimized and the cycle performance of the battery can be improved.

[0093] 3D printing technology encompasses a wide variety of types, and the appropriate process can be selected based on the type of printing raw materials used. For example, when the support layer material is polyacrylate and a conductive agent, the printing raw materials can include vinyl-containing monomers, photopolymers, photoinitiators, and conductive agents. Acrylate monomers can be selected from alkyl acrylates, hydroxy methacrylates, glycidyl methacrylates, isobornyl acrylate, tetrahydrofuran methyl acrylate, styrene, 1,6-hexanediol diacrylate, triethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PETA), dipentaerythritol pentaacrylate (DPPA), etc. Photopolymers are materials that can undergo a chemical reaction when exposed to light (such as ultraviolet or visible light), achieving curing or cross-linking. They are macromolecular monomer structures with chemically reactive groups. Examples include polyurethane acrylates, polyester acrylates, epoxy resin acrylates, and polyether resin acrylates. Photoinitiators can be selected from pyrolysis-type free radical photoinitiators and hydrogen-abstraction-type free radical photoinitiators. Examples of pyrolysis-type free radical photoinitiators include benzoin and its derivatives, α,α-diethoxyacetophenone, α-hydroxyalkyl phenyl ketone photoinitiators, and acylphosphine oxide photoinitiators (such as TPO, TEPO, etc.); examples of hydrogen-abstraction-type free radical photoinitiators include benzophenone, thioxanthone and its derivatives. When using the above materials as printing raw materials, stereolithography (SLA) printing can be used, which utilizes an ultraviolet laser beam to irradiate the liquid photosensitive resin, causing it to cure rapidly.

[0094] When the support layer material is polypropylene and a conductive agent, or polyethylene and a conductive agent, the printing raw material can be polypropylene and a conductive agent, or polyethylene and a conductive agent, and the printing method can be fused deposition modeling, selective laser sintering, etc.

[0095] In some embodiments, a negative electrode sheet is provided as a printing substrate; vinyl-containing monomers, photosensitive oligomers, photoinitiators and conductive agents are mixed as printing raw materials to obtain printing ink; the size and other information of the printing pattern are input into the 3D printer, and the support layer structure is printed on the surface of the negative electrode sheet using the printing ink; the printed negative electrode sheet is then irradiated with a UV lamp to rapidly cure the printing ink.

[0096] In some embodiments, a negative electrode sheet is provided as a printing substrate; polypropylene and a conductive agent are mixed as printing materials to obtain printing ink; information such as the size of the printing pattern is input into a 3D printer, and the support layer structure is printed on the surface of the negative electrode sheet using the printing ink.

[0097] In some embodiments, a negative electrode sheet is provided as the printing substrate; polypropylene, a conductive agent, and a metal compound with an affinity for alkali metals are mixed as a first printing ink; information such as the size of the printing pattern is input into a 3D printer, and the affinity layer of the support layer is printed on the surface of the negative electrode sheet using the first printing ink; then, polypropylene and a conductive agent are mixed as a second printing ink, and a conductive layer is directly printed on top of the affinity layer; then, polypropylene is used as a third printing ink to directly print a polymer layer on top of the conductive layer. In this way, a gradient distribution of alkali metal affinity from high to low can be formed from the negative electrode sheet to the separator.

[0098] In some embodiments, a separator membrane is provided as a printing substrate; polypropylene is used as a first printing ink, and information such as the size of the printing pattern is input into a 3D printer. The polymer layer of the support layer is printed onto the surface of the separator membrane using the first printing ink; then, polypropylene and a conductive agent are mixed as a second printing ink, and a conductive layer is directly printed on top of the polymer layer; then, polypropylene, a conductive agent, and a metal compound with an affinity for alkali metals are mixed as a third printing ink, and an affinity layer is directly printed on top of the conductive layer. In this way, a gradient distribution of alkali metal affinity from high to low can be formed from the negative electrode sheet to the separator membrane.

[0099] In some embodiments, the 3D printing process parameters are as follows: nozzle size is 5μm to 100μm; optionally, the nozzle size can be 10μm to 50μm; printing speed is 1m / min to 10m / min; optionally, the printing speed can be 1m / min to 5m / min. By adjusting the nozzle size, printing accuracy can be improved. The above nozzle sizes can print finer wall thicknesses, smaller gaps, and more complex geometries. By controlling the printing speed, printing accuracy and detail can be improved, and surface roughness and internal defects can be reduced. By controlling the nozzle size and printing speed, a support layer with uniform pore distribution and appropriate pore size is obtained, which significantly reduces the non-uniform flux of alkali metals during the deposition process.

[0100] Thirdly, embodiments of this application provide an alkali metal battery, including the electrode assembly described above. Due to the use of the electrode assembly, the battery's cycle expansion force is significantly improved, and its cycle performance is enhanced.

[0101] Alkali metal batteries are a type of battery that primarily uses alkali metals as the negative electrode active material. Examples of alkali metal batteries include lithium metal batteries, sodium metal batteries, and potassium metal batteries.

[0102] The following is a detailed description of alkali metal batteries and their components.

[0103] Please refer to Figure 10 , Figure 10This is a schematic diagram of the structure of the electrode 10 in some embodiments of this application. The electrode 10 includes a current collector 1 and an active material layer 2, the active material layer 2 being disposed on at least one side of the current collector 1.

[0104] Current collector 1 refers to the component used to collect current. Depending on the application, current collector 1 can be either a negative electrode current collector or a positive electrode current collector. When current collector 1 is a negative electrode current collector, the corresponding active material layer 2 coated on the negative electrode current collector is a negative electrode active material layer, and the resulting electrode 10 is a negative electrode electrode. When current collector 1 is a positive electrode current collector, the corresponding active material layer 2 coated on the positive electrode current collector is a positive electrode active material layer, and the resulting electrode 10 is a positive electrode electrode. Taking a sodium metal battery as an example, optionally, the negative electrode current collector is copper foil, and the positive electrode current collector is aluminum foil. Furthermore, current collector 1 can have various shapes, such as strips or squares, and is not limited here.

[0105] The active material layer 2 includes an active material, a conductive agent, and a binder. The active material refers to the material that participates in the electrochemical oxidation / reduction reaction. Optionally, the active material is a powder. When the active material layer 2 is the negative electrode material layer, the active material is the negative electrode active material. When the active material layer 2 is the positive electrode material layer, the active material is the positive electrode active material. Taking a sodium metal battery as an example, the negative electrode material can be a sodium metal negative electrode (including no negative electrode); the positive electrode material includes, but is not limited to, NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, Na... 0.67 MO2 (M includes at least two of Fe, Co, Cr, Mn, Ni, V, Ti, and Mo), NaMO2 (M includes at least two of Fe, Co, Ni, V, Ti, and Mo), NaFePO4, NaMnPO4, NaCoPO4, Na4Fe3(PO4)2O7, Na3V2(PO4)2F3, Na3V2(PO4)3, Prussian blue, Prussian white, and one or more of their respective modified compounds. The conductive agent refers to the material that collects microcurrents between active materials and between the active material and current collector 1. The conductive agent can be, but is not limited to, conductive graphite, carbon nanotubes, acetylene black, etc. The binder is the material that binds the active materials together to enhance the electronic contact between the active material and the conductive agent, and between the active material and current collector 1. The binder can be, but is not limited to, styrene-butadiene rubber (SBR), acrylonitrile, acrylates, polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), etc.

[0106] The current collector 1 has a first surface and a second surface opposite to each other along the thickness direction of the current collector 1. At least one side of the current collector 1 includes the first surface and / or the second surface of the current collector 1. It is understood that the active material layer 2 may be disposed on the first surface, or on the second surface, or the active material layer 2 may be disposed on both the first surface and the second surface.

[0107] Please refer to Figure 11 , Figure 11 This is a schematic diagram of the structure of the electrode assembly 20 in some embodiments of this application. The electrode assembly 20 is a component in the battery where electrochemical reactions occur. The electrode assembly 20 is mainly formed by winding or stacking an integrated electrode structure consisting of a negative electrode 101 and a positive electrode 102. A separator 103 is typically provided between adjacent negative electrode 101 and positive electrode 102. A negative electrode tab 104 is connected to the negative electrode current collector, and a positive electrode tab 105 is connected to the positive electrode current collector. The support layer in this embodiment of the application ( Figure 11 (Not shown) It can be disposed on the surface of the negative electrode 101 facing the separator 103, or it can be disposed on the surface of the separator 103 facing the negative electrode 101.

[0108] [Negative electrode plate]

[0109] The negative electrode 101 includes a negative electrode current collector and a negative electrode material layer, the negative electrode material layer being coated on the surface of the negative electrode current collector. Taking a sodium metal battery as an example, the material of the negative electrode current collector can be copper. The negative electrode can include a sodium metal negative electrode (including no negative electrode), a carbon material negative electrode, and other non-carbon material negative electrodes.

[0110] It should be noted that "no negative electrode" refers to a secondary battery that does not use a negative electrode material. Taking a sodium metal battery without a negative electrode as an example, its working principle is as follows: During charging, sodium ions in the sodium-containing positive electrode material pass through the separator and combine with electrons transmitted through the external circuit to form sodium metal, which is then deposited on the negative electrode current collector. During discharging, the sodium metal on the negative electrode current collector dissolves and returns to the electrolyte, passes through the separator, and is re-embedded in the positive electrode material.

[0111] In some embodiments, the negative electrode active material may further include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, and tin-based materials.

[0112] In some embodiments, the negative electrode active material may also include a binder. Examples of binders include styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0113] In some embodiments, the negative electrode active material further includes a conductive agent. Examples of conductive agents include superconducting carbon, acetylene black, carbon black, Ketjen black, carbon nanotubes, graphene, etc.

[0114] In some embodiments, the negative electrode sheet of a sodium metal battery can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, in a solvent to form a negative electrode slurry, coating the negative electrode slurry onto a negative electrode current collector, and obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0115]

Positive Electrode

[0116] The positive electrode 102 includes a positive current collector and a positive active material layer, with the positive active material layer coated on the surface of the positive current collector. Taking a sodium metal battery as an example, the material of the positive current collector can be aluminum, and the positive material layer includes the positive electrode material, which can be sodium vanadium phosphate, sodium iron pyrophosphate, etc.

[0117] In some embodiments, the positive electrode sheet of a sodium metal battery can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent to form a positive electrode slurry, coating the positive electrode slurry onto a positive current collector, and obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0118]

Isolation Film

[0119] The separator 103 is a porous plastic film that allows alkali metal ions in the electrolyte to pass through freely, but isolates the negative electrode 101 and the positive electrode 102, preventing electrons inside the battery from passing through freely. The separator 103 can be made of PP (polypropylene) or PE (polyethylene), etc. Organic or inorganic composite coatings can also be applied to the separator 103, including but not limited to ceramic particle coatings, metal oxide coatings, polymer adhesive layers, etc.

[0120] Fourthly, embodiments of this application provide an electrical device including the aforementioned alkali metal battery. By employing the alkali metal battery of this application, the operational stability of the electrical device is improved.

[0121] The batteries disclosed in some embodiments of this application can be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system incorporating the batteries disclosed in this application can be used to construct such an electrical device.

[0122] For ease of explanation, the following embodiments will be described using a vehicle 50 as an example of an electrical device according to an embodiment of this application.

[0123] Please refer to Figure 12 , Figure 12This is a schematic diagram of the structure of a vehicle 50 provided in some embodiments of this application. A battery 40 is disposed inside the vehicle 50, and the battery 40 may be located at the bottom, front, or rear of the vehicle 50. The battery 40 can be used to power the vehicle 50; for example, the battery 40 can serve as the operating power source for the vehicle 50. The vehicle 50 may also include a controller 501 and a motor 502. The controller 501 is used to control the battery 40 to supply power to the motor 502, for example, to meet the power needs of the vehicle 50 during starting, navigation, and driving.

[0124] In some embodiments of this application, the battery 40 can not only serve as the operating power source for the vehicle 50, but also as the driving power source for the vehicle 50, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 50.

[0125] In some embodiments of this application, battery 40 may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed configurations via a busbar.

[0126] A single battery cell can be a rechargeable battery. A rechargeable battery is a battery cell that can be recharged after it has been discharged, allowing the active materials to be activated and the cell to continue to be used.

[0127] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc.

[0128] Fifthly, embodiments of this application provide an energy storage device, including the aforementioned alkali metal battery.

[0129] This application provides an energy storage device including one or more battery clusters to improve the voltage and capacity of the energy storage device. The battery cluster may include multiple battery devices connected in series via a busbar to increase the voltage of the energy storage device. Each battery device may include one or more individual battery cells.

[0130] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, energy storage devices can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours.

[0131] The following description is based on specific embodiments.

[0132] Example 1

[0133] In this embodiment, a support layer is disposed on the surface of the negative electrode sheet. The support layer has a plurality of through holes, which are circular and extend through the thickness of the support layer. The diameter of each through hole is 300 μm. The area of ​​the support layer covering the surface of the negative electrode sheet is 20% of the surface area. The thickness of the support layer is 100 μm. The materials of the support layer include polyacrylate and conductive carbon black.

[0134] (1) Preparation of cathode materials

[0135] The positive electrode active material sodium iron pyrophosphate, the conductive agent carbon black (Super P), and the binder polyvinylidene fluoride (PVDF) were thoroughly mixed in an appropriate amount of NMP solvent at a weight ratio of 90:5:5 to form a uniform positive electrode slurry. The positive electrode slurry was then coated onto the surface of the positive electrode current collector aluminum foil, with a coating weight ≤25mg / cm². 2 After drying and cold pressing, a positive electrode sheet is obtained;

[0136] (2) Preparation of negative electrode sheet

[0137] Carbon nanotubes (CNTs) and sodium carboxymethyl cellulose (CMC) were thoroughly mixed in an appropriate amount of deionized water at a weight ratio of 50:50 to form an interface modification layer slurry. The interface modification layer slurry was then coated onto the surface of the copper foil of the negative electrode current collector to a thickness of 5 μm.

[0138] (3) Preparation of support layer

[0139] Using the negative electrode sheet as the printing substrate, a mixture of 35g methyl acrylate, 54g polyether acrylate resin, 1g benzoin, and 10g conductive carbon black was prepared as the printing ink. The dimensions of the printing pattern were entered into the 3D printer, and printing was then performed on one surface of the negative electrode sheet. The 3D printer nozzle size was 5μm, and the printing speed was 1m / min. The ink was then rapidly cured by UV lamp irradiation.

[0140] (4) Separating membrane

[0141] A polyethylene film with a thickness of 9 μm was used as the separator.

[0142] (5) Electrolyte: Dissolve fully dried NaPF6 in diethylene glycol dimethyl ether (DEGDME) to prepare an electrolyte with a concentration of 1 mol / L.

[0143] (6) Battery assembly

[0144] A sodium metal battery is obtained by stacking a positive electrode, a separator, and a negative electrode in sequence to form a single-layer laminated cell, wherein the side of the negative electrode with a support layer is positioned opposite the separator.

[0145] Example 2

[0146] The difference between Example 2 and Example 1 is that the diameter of the through holes in the support layer is 10 μm.

[0147] Example 3

[0148] The difference between Example 3 and Example 1 is that the diameter of the through holes in the support layer is 1400 μm.

[0149] Example 4

[0150] The difference between Example 4 and Example 1 is that the area of ​​the support layer covering the surface of the negative electrode sheet accounts for 5% of the surface area.

[0151] Example 5

[0152] The difference between Example 5 and Example 1 is that the area of ​​the support layer covering the surface of the negative electrode sheet accounts for 50% of the surface area.

[0153] Example 6

[0154] The difference between Example 6 and Example 1 is that the support layer has an affinity layer with a thickness of 3 μm.

[0155] The preparation method differs from that in Example 1 in that: 35g of methyl acrylate, 54g of polyether resin acrylate, 1g of benzoin, and 10g of conductive carbon black are mixed as the first printing ink; then 5g of silver nanoparticles are added to the first printing ink and mixed evenly to form the second printing ink; the dimensions and other information of the printing pattern are input into the 3D printer, and the affinity layer of the support layer is printed on the surface of the negative electrode sheet using the second printing ink, which is then rapidly cured by UV irradiation; then, the remaining support layer is directly printed on top of the affinity layer using the first printing ink, which is then rapidly cured by UV irradiation.

[0156] Example 7

[0157] The difference between Example 7 and Example 1 is that the support layer has a polymer layer with a thickness of 3 μm.

[0158] The preparation method differs from that in Example 1 in that: 35g of methyl acrylate, 54g of polyether resin acrylate, and 1g of benzoin are mixed as the first printing ink, and then 10g of conductive carbon black is added to the first printing ink and mixed evenly to form the second printing ink; the size and other information of the printing pattern are input into the 3D printer, and the conductive part of the support layer is printed on the surface of the negative electrode sheet using the second printing ink, and then cured quickly by UV lamp irradiation; then, the polymer layer is directly printed on top of the conductive part using the first printing ink, and then cured quickly by UV lamp irradiation.

[0159] Example 8

[0160] The difference between Example 8 and Example 6 is that the support layer has an affinity layer and a polymer layer, both of which have a thickness of 3 μm.

[0161] The preparation method differs from that in Example 1 in the following ways: 35g of methyl acrylate, 54g of polyether resin acrylate, and 1g of benzoin are mixed as the first printing ink. Then, 5g of silver nanoparticles are added to the first printing ink and mixed evenly to form the second printing ink. The dimensions and other information of the printing pattern are input into the 3D printer. The second printing ink is used to print the affinity layer of the support layer onto the surface of the negative electrode sheet, which is then rapidly cured by UV irradiation. Next, 10g of conductive carbon black is added to the first printing ink and mixed evenly to form the third printing ink. The third printing ink is then used to directly print the conductive layer above the affinity layer, which is then rapidly cured by UV irradiation. Finally, the first printing ink is used to directly print the polymer layer above the conductive layer, which is also rapidly cured by UV irradiation.

[0162] Example 9

[0163] The difference between Example 9 and Example 8 is that the support layer has several uniformly arranged through holes.

[0164] Example 10

[0165] The difference between Example 10 and Example 1 is that the material of the support layer includes polypropylene and conductive carbon black.

[0166] The difference between its preparation method and the preparation method in Example 1 is that: the negative electrode sheet is used as the printing substrate, 90g of polypropylene and 10g of conductive carbon black are mixed as printing ink, the size of the printing pattern is input in the 3D printer, and then the printing is performed on the surface of the negative electrode sheet to obtain the support layer.

[0167] Example 11

[0168] The difference between Example 11 and Example 1 is that the support layer includes several identical support units arranged in an array, such as... Figure 6 The support unit shown is a cuboid, and the width of the gap between any two adjacent support units is 300 μm.

[0169] Example 12

[0170] The difference between Example 12 and Example 1 is that the support layer is disposed on the surface of the isolation membrane.

[0171] The difference between its preparation method and the preparation method in Example 1 is that: the isolation film is used as the printing substrate, and 35g of methyl acrylate, 54g of polyether resin acrylate, 1g of benzoin and 10g of conductive carbon black are mixed as printing ink. The size of the printing pattern is entered in the 3D printer, and then printed on one of the surfaces of the isolation film. It is then cured quickly by UV lamp irradiation.

[0172] Comparative Example 1

[0173] The difference between Comparative Example 1 and Example 1 is that no support layer is provided between the negative electrode sheet and the separator.

[0174] Performance testing

[0175] To verify the progressiveness of the embodiments of this application, the samples of the embodiments and comparative examples were subjected to the following tests:

[0176] 1. Testing of the thickness of the support layer, the diameter of the through holes, the width of the gap between two adjacent support units, and the area of ​​the support layer covering the substrate surface: Using an optical microscope, longitudinal or transverse interface tests of the sample are collected, and the results are observed and measured under the microscope.

[0177] Battery performance test

[0178] 1. First Coulomb Efficiency Test of the Battery

[0179] The capacity measured by charging the battery at 0.02C for 600 minutes at 45℃ is marked as C0. Then, it is charged at 0.33C to 3.65V at 25℃, and then charged at a constant voltage of 3.65V to 0.05C. The measured capacity is marked as C1. Finally, it is discharged at 0.33C to 2V. The measured capacity is marked as D0. The initial coulombic efficiency of the secondary battery is ICE = D0 / (C0+C1)×100%.

[0180] 2. Battery cycle performance test

[0181] A sodium metal battery is charged at a constant current of 0.33C to 3.65V, and then discharged at a constant current of 1C to 1.5V. This constitutes one charge-discharge cycle. Using the initial discharge capacity as 100%, calculate the capacity retention rate after 200 cycles. Capacity retention rate (%) after 200 cycles = (Discharge capacity of the 200th cycle / Initial discharge capacity) × 100%.

[0182] Table 1

[0183]

[0184] As shown in Table 1, the initial coulombic efficiency and capacity retention after 200 battery cycles of Examples 1 to 12 are all higher than those of Comparative Example 1, indicating that the support layer of this application can effectively improve the initial efficiency and cycle performance of the battery. Specifically, the pore size of the support layer in Example 1 is 300 μm, which is more suitable than that of Examples 2 and 3, thus resulting in a better capacity retention after 200 cycles. The support layer in Example 1 covers 20% of the substrate surface area, which, compared to Examples 4 and 5, indicates a more suitable porosity and prism thickness, thus resulting in a better capacity retention after 200 cycles compared to Examples 4 and 5. An affinity layer was introduced into the support layer of Example 6, a polymer layer was introduced into the support layer of Example 7, and both an affinity layer and a polymer layer were introduced into the support layer of Example 8. The cycle performance of Examples 6 to 8 was better than that of Example 1, and Example 8 had the best performance among all examples. This indicates that the support layer with both the affinity layer and the polymer layer is more conducive to the uniform and dense deposition of alkali metals, thereby improving the cycle performance of the battery.

[0185] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrode assembly, characterized in that, It includes a positive electrode, a negative electrode, a separator, and a support layer, wherein the support layer is disposed on the surface of a substrate, and the surface of the substrate includes either of the two surfaces of the negative electrode and the separator that are opposite to each other; The support layer has a plurality of through holes, which are disposed through the thickness of the support layer; and / or, the support layer includes a plurality of support units, with a gap between two adjacent support units.

2. The electrode assembly according to claim 1, characterized in that, The support layer is a 3D printed structure.

3. The electrode assembly according to claim 1 or 2, characterized in that, The diameter of the through hole is 2μm to 1500μm; and / or the width of the gap between two adjacent support units is 2μm to 1500μm.

4. The electrode assembly according to any one of claims 1 to 3, characterized in that, The diameter of the through hole is 2μm to 300μm; and / or the width of the gap between two adjacent support units is 2μm to 300μm.

5. The electrode assembly according to any one of claims 1 to 4, characterized in that, The area of ​​the support layer covering the surface of the substrate is 5% to 50% of the surface area of ​​the substrate.

6. The electrode assembly according to any one of claims 1 to 5, characterized in that, The thickness of the support layer is 5μm to 300μm.

7. The electrode assembly according to any one of claims 1 to 6, characterized in that, The material of the support layer includes a polymer and a conductive agent; wherein... The polymer includes at least one of polyacrylate, polypropylene, and polyethylene; and / or the conductive agent includes at least one of conductive carbon black, carbon fiber, carbon nanotube, and graphene.

8. The electrode assembly according to any one of claims 1 to 7, characterized in that, The support layer has an affinity layer located in the thickness direction, the affinity layer containing a metal element that has an affinity for alkali metals; the affinity layer is located at one end of the support layer near the negative electrode sheet.

9. The electrode assembly according to claim 8, characterized in that, The metallic element includes at least one selected from Au, Ag, Mg, Zn, Sn, Sb, In, and Ti; and / or, With the total mass of the support layer being 100%, the mass percentage of the metal element is 0.05% to 5%.

10. The electrode assembly according to claim 8, characterized in that, The thickness of the affinity layer is 0.1 μm to 10 μm.

11. The electrode assembly according to any one of claims 1 to 10, characterized in that, The support layer has a polymer layer located in the thickness direction; the polymer layer is located at one end of the support layer opposite to the negative electrode sheet.

12. The electrode assembly according to claim 11, characterized in that, The thickness of the polymer layer is 1% to 50% of the thickness of the support layer; and / or, The polymer layer is made of at least one of polyacrylate, polypropylene, and polyethylene.

13. The electrode assembly according to any one of claims 1 to 12, characterized in that, The support layer has a plurality of identical through holes evenly distributed; and / or, the support layer includes a plurality of identical support units arranged in an array.

14. A method for preparing an electrode assembly, characterized in that, Includes the following steps: Based on the preset three-dimensional model of the support layer, using polymer and conductive agent as raw materials, 3D printing is performed on either of the two surfaces opposite to each other, namely the negative electrode sheet and the separator, to obtain the support layer. The support layer has a plurality of through holes, which are disposed through the thickness of the support layer; and / or, the support layer includes a plurality of support units, with a gap between two adjacent support units; The positive electrode, separator, and negative electrode are assembled in sequence to form the electrode assembly.

15. The method for preparing the electrode assembly according to claim 14, characterized in that, The 3D printing process parameters are as follows: nozzle size is 5μm to 100μm; printing speed is 1m / min to 10m / min.

16. An alkali metal battery, characterized in that, Electrode assemblies including those prepared by any one of claims 1 to 13 and / or any one of claims 14 to 15.

17. An electrical appliance, characterized in that, Including the alkali metal battery as described in claim 16.

18. An energy storage device, characterized in that, Including the alkali metal battery as described in claim 16.

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